1) Field of the invention
The invention relates generally to an apparatus for washing semiconductor materials, and more specifically to a blowing port through which clean air flows out over a plurality of washing tanks disposed within a case.
2) Description of the prior art
In commonly accepted technique, this type of washing apparatus as shown in FIGS. 7-9 has been known. This washing apparatus has been used for washing semiconductor wafers as semiconductor materials which are housed in a carrier. In the carrier a suitable number of semiconductor wafers are set as one lot. As shown in FIG. 7, a plurality of washing tanks are located within a case, usually in two rows of which one row is consisted of tank or tanks for water including cleaning chemicals, and another row being consisted of tank or tanks for pure water used for final washing. If vapor generated in the cleaning chemical tanks enters the adjacent final washing tanks, it will influence on upper portion of semiconductor wafers in the tanks, which will result in stain film on the upper portion of the wafers.
In order to avoid this defect, the case of the washing apparatus has a blowing port at one side thereof and a suction port at opposite side of the case to flow clean air from the blowing port over the respective washing tanks to the suction port, to thereby prevent vapor of the cleaning chemical tanks from entering the final washing tanks. The clean air is fed to the blowing port by a fan through air filter.
Further, this type of washing apparatus is disposed in a clean room, and also clean air is discharged downwards through the ceiling of the clean room. Accordingly, the suction port serves to receive clean air flown from both the blowing port and the ceiling of the clean room.
One type of the conventional blowing ports is formed with many holes at the end thereof as shown in FIG. 8, and clean air flows out through the holes. Another type of the blowing port, as shown in FIG. 9, has an upwards extending duct of which uppermost portion is curved to generate a substantially horizontal air flow and is formed convergently to the end thereof.
Since the described former type in prior art discharges clean air through many holes, clean air flows out to a wider area, which results in turbulence in air flow. Thus this type is not preferable. Also, the latter type has a convergent discharge end portion, which will form a rather laminar air flow. However, when wafer carriers are inserted into or taken out from the washing tanks, there will be water splashes which will enter the interior of the blowing port. The air filter in the duct of the blowing port will be damaged with such water splashes.